01/03: nginx: mirror: Honor upstream's 'Cache-Control' headers.

[Ludovic Courtès]

civodul pushed a commit to branch master
in repository maintenance.

commit 10b27972a4348ce13f9d79c6e68cc9574e0128fe
Author: Ludovic Courtès <address@hidden>
Date:   Mon Aug 28 15:10:19 2017 +0200

    nginx: mirror: Honor upstream's 'Cache-Control' headers.
    
    'guix publish -C' does the right thing, so trust it.
    
    * hydra/nginx/mirror-locations.conf (.narinfo): Remove
    most 'proxy_cache_valid' and 'proxy_ignore_headers' directives.
---
 hydra/nginx/mirror-locations.conf | 23 +++++++----------------
 1 file changed, 7 insertions(+), 16 deletions(-)

diff --git a/hydra/nginx/mirror-locations.conf 
b/hydra/nginx/mirror-locations.conf
index 9278331..34ab3f9 100644
--- a/hydra/nginx/mirror-locations.conf
+++ b/hydra/nginx/mirror-locations.conf
@@ -72,29 +72,20 @@ location ~ \.narinfo$ {
     proxy_read_timeout 2s;
     proxy_send_timeout 2s;
 
-    # Enable caching for narinfo files, to avoid recomputing nar signatures.
-    #
-    # Note: Avoid caching narinfos for too long to avoid a situation
-    # where we have the narinfo but don't have the corresponding nar
-    # and cannot have it.
+    # Cache for narinfo files.  We assume that upstream runs 'guix
+    # publish' and provides 'Cache-Control' headers that we can just
+    # blindly honor.
     proxy_cache narinfo;
-    proxy_cache_valid 200 10d;  # cache hits for 10 days
-    proxy_cache_valid 504 5m;  # timeout, when hydra.gnu.org is overloaded
-    proxy_cache_valid any 10m;  # cache misses/others for 10m
 
-    # Use the above TTLs, not those advertised by hydra.gnu.org.
-    proxy_ignore_headers Expires Cache-Control;
+    proxy_cache_valid 504 5m;  # timeout, when hydra.gnu.org is overloaded
 
-    # Add 'Expires' and 'Cache-Control' response headers so clients
-    # such as 'guix substitute' know how long they can cache it.
-    # Override the headers coming from hydra.gnu.org.
-    proxy_hide_header    Expires;
-    proxy_hide_header    Cache-Control;
+    # Advertise a shorter TTL than what upstream provides to be on the
+    # safe side.
     expires 7d;
 
     proxy_ignore_client_abort on;
 
-    # We need to hide and ignore the Set-Cookie header
+    # We need to hide and ignore Hydra's Set-Cookie header
     # to enable caching.
     proxy_hide_header    Set-Cookie;
     proxy_ignore_headers Set-Cookie;